1. Field of the Invention
The present invention relates to a tunnel reinforcement structure and a tunnel construction method, and more particularly, to a tunnel reinforcement structure and a tunnel construction method capable of controlling displacement using pressurization, wherein a pressurizing bag is provided between the excavated inner surface of the ground and steel ribs so as to recover or to the highest degree restrain the ground displacement and ground surface settlement occurring around an excavation face of the tunnel.
Further, the present invention relates to a tunnel reinforcement structure and a tunnel construction method capable of controlling displacement using pressurization, wherein reinforcements and face bolts resist the external forces applied in a vertical or horizontal direction and the external forces locally generated, during excavation, as an integral body with each other, thereby improving the stability of the excavation.
2. Background of the Related Art
According to the excavation work carried out to pass through the ground under a given structure like expressways or railways, generally, steel pipes having a diameter of more than 800 mm are first forcedly inserted into the ground for tunnel excavation, and next, steel pipes are penetratedly arranged in the excavation process of the soil inside the inserted steel pipes. As the above processes are repeatedly carried out, the plurality of steel pipes is disposed to surround the outside of a concrete box structure to be installed, and after the steel pipes adjacent horizontally to each other are connected, concrete is cast to them.
After the steel pipes into which the concrete is filled are disposed on the ground, next, the soil surrounded by the steel pipes are excavated, thereby building the concrete box structure in the excavated space surrounded by the steel pipes. According to such conventional construction method, the large diameter steel pipes with large stiffness having a diameter of more than 800 mm are first installed before the excavation for construction of the concrete box structure, so as to prevent ground displacement from occurring during the excavation.
According to the conventional construction method, however, a relatively large construction area is needed to install a reaction force plate, an oil jack and the like as used for steel pipe jacking, and high construction costs and long construction period are also needed because of the installation of very expensive large diameter steel pipes and the excavation and welding carried out under the steel pipes.